1. Field of the Invention
This invention relates to system virtualization, and, more particularly, to Virtual Machine technology.
2. Description of the Related Art
One of the current issues in Virtual Machine implementation is management of relatively scarce physical resources, given a fairly large footprint of each Virtual Machine. For example, situations where a Virtual Machine is used as a webserver are common, as well as where multiple such Virtual Machines are running on the same physical computer. As such, the footprint of each Virtual Machine, particularly as it affects memory and disk space, becomes of particular concern. As a practical matter, many modern operating systems require several gigabytes of disk space (and sometimes a comparable amount of disk space allocated to user applications), as well as several megabytes of physical memory that needs to be allocated to each Virtual Machine, to account for the guest operating system as well as the user applications running inside each Virtual Machine.
A method for sharing memory pages is described in U.S. Pat. No. 6,789,156 to Waldspurger, filed Sep. 7, 2004 for content-based, transparent sharing of memory units, where only a part of memory space may be handled using a number of checking procedures.
In sum, there is a need to decrease the amount of scarce resources consumed by each Virtual Machine, in order to be able to increase the density of Virtual Machines on each physical system.